title: Parkin mediates beclin-dependent autophagic clearance of defective mitochondria and ubiquitinated Abeta in AD models.
abstract: Intraneuronal amyloid-β (Aβ) may contribute to extracellular plaque deposition, the characteristic pathology of Alzheimer's disease (AD). The E3-ubiquitin ligase parkin ubiquitinates intracellular proteins and induces mitophagy. We previously demonstrated that parkin reduces Aβ levels in lentiviral models of intracellular Aβ. Here we used a triple transgenic AD (3xTg-AD) mouse, which over-expresses APP(Swe), Tau(P301L) and harbor the PS1(M146V) knock-in mutation and found that lentiviral parkin ubiquitinated intracellular Aβ in vivo, stimulated beclin-dependent molecular cascade of autophagy and facilitated clearance of vesicles containing debris and defective mitochondria. Parkin expression decreased intracellular Aβ levels and extracellular plaque deposition. Parkin expression also attenuated caspase activity, prevented mitochondrial dysfunction and oxidative stress and restored neurotransmitter synthesis. Restoration of glutamate synthesis, which was independent of glial-neuronal recycling, depended on mitochondrial activity and led to an increase in γ-amino butyric acid levels. These data indicate that parkin may be used as an alternative strategy to reduce Aβ levels and enhance autophagic clearance of Aβ-induced defects in AD. Parkin-mediated clearance of ubiquitinated Aβ may act in parallel with autophagy to clear molecular debris and defective mitochondria and restore neurotransmitter balance.
authors.affiliation: Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20007, USA.
authors.forename: Preeti J
authors.initials: PJ
authors.lastname: Khandelwal
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Herman
authors.forename: Hyang-Sook
authors.initials: HS
authors.lastname: Hoe
authors.forename: G William
authors.initials: GW
authors.lastname: Rebeck
authors.forename: Charbel E-H
authors.initials: CE
authors.lastname: Moussa
mesh_terms: D000544:Alzheimer Disease / Q000235:genetics* / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D001343:Autophagy; D000071186:Beclin-1; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002540:Cerebral Cortex / Q000503:physiopathology / Q000648:ultrastructure; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D055879:Gene Knock-In Techniques; D005822:Genetic Vectors; D007150:Immunohistochemistry / Q000379:methods; D016086:Lentivirus / Q000378:metabolism; D013058:Mass Spectrometry; D051379:Mice; D008822:Mice, Transgenic; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology*; D009154:Mutation; D018377:Neurotransmitter Agents / Q000032:analysis / Q000378:metabolism; D018384:Oxidative Stress; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D016229:Amyloid beta-Peptides; D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; C115010:Becn1 protein, mouse; D018377:Neurotransmitter Agents; D044767:Ubiquitin-Protein Ligases; C111567:parkin protein; C505409:Casp3 protein, mouse; C506434:Casp9 protein, mouse; D053148:Caspase 3; D053453:Caspase 9